Sensitive multi-species photoacoustic gas detection based on mid-infrared supercontinuum source and miniature multipass cell

Abstract

We report multipass broadband photoacoustic spectroscopy of trace gases in the mid-infrared. The measurement principle of the sensor relies on supercontinuum-based Fourier transform photoacoustic spectroscopy (FT-PAS), in which a scanning...

Detection of gaseous nerve agent simulants with broadband photoacoustic spectroscopy

“…The experimental setup illustrated in Fig. 1 closely resembles our previously reported system (Mikkonen et al, 2022b) and has a footprint of about 40 kg and 50 cm × 35 cm × 35 cm when enclosed tightly. The radiation source is a home-built SC (Mikkonen et al, 2018;Amiot et al, 2017), where sub-nanosecond pulses from an erbium-doped fiber laser (1547 nm, 6464 cm − 1 ) are injected into two successive optical fibers (a 4-m-long silica dispersion-shifted fiber and an 8.3-m-long fluoride fiber) at 90 kHz repetition rate.…”

“…These two complementary methods have long been combined in Fourier transform photoacoustic spectroscopy (FT-PAS) (Farrow et al, 1978), which utilizes the parallel down-conversion of optical frequencies of a broadband light into acoustic frequencies, followed by the excitation of absorption-induced pressure waves through periodic thermal relaxations. However, only recent advances in light sources and pressure transducers have fully realized the potential of the technique (Karhu et al, 2019;Mikkonen et al, 2018Mikkonen et al, , 2022bSadiek et al, 2018;Wildi et al, 2020). For example, we have previously implemented a supercontinuum (SC) source and a cantilever microphone in a FT-PAS system, which provides fast and selective sensing of hydrocarbons with ppb-level detection limits in a few milliliter sample volume (Mikkonen et al, 2022b).…”

“…However, only recent advances in light sources and pressure transducers have fully realized the potential of the technique (Karhu et al, 2019;Mikkonen et al, 2018Mikkonen et al, , 2022bSadiek et al, 2018;Wildi et al, 2020). For example, we have previously implemented a supercontinuum (SC) source and a cantilever microphone in a FT-PAS system, which provides fast and selective sensing of hydrocarbons with ppb-level detection limits in a few milliliter sample volume (Mikkonen et al, 2022b).…”

Light intensity correction for quartz-enhanced photoacoustic spectroscopy using photothermal baseline

“…Moreover, the PD or power meter will entail a high cost and complexity especially for mid-infrared or terahertz laser-based QEPAS system. Furthermore, it can be much more complex to handle light intensity drifts when the light system comprises multiple lasers of different wavelengths or instantaneous broadband spectral coverage [14][15][16][17], especially when the responsivity of the PD or the power meter varies with wavelength.…”

Detection of Gaseous Nerve Agent Simulants with Broadband Photoacoustic Spectroscopy

“…These two complementary methods have long been combined in Fourier transform photoacoustic spectroscopy (FT-PAS) (Farrow et al, 1978), which utilizes the parallel down-conversion of optical frequencies of a broadband light into acoustic frequencies, followed by the excitation of absorption-induced pressure waves through periodic thermal relaxations. However, only recent advances in light sources and pressure transducers have fully realized the potential of the technique (Karhu et al, 2019;Mikkonen et al, 2018Mikkonen et al, , 2022bSadiek et al, 2018;Wildi et al, 2020). For example, we have previously implemented a supercontinuum (SC) source and a cantilever microphone in a FT-PAS system, which provides fast and selective sensing of hydrocarbons with ppb-level detection limits in a few milliliter sample volume (Mikkonen et al, 2022b).…”